Inoculation of ophiostomatoid fungi in loblolly pine trees increases the presence of subterranean termites in fungal lesions

Abstract

Many bluestain (ophiostomatoid) fungi are inoculated into trees via bark beetle activity, but their ecological roles are not fully understood, particularly for interactions with invertebrates outside bark beetle and phoretic mite associations. Recently, correlational field studies and small-scale laboratory feeding trials have demonstrated subterranean termites have increased presence on and preferential feeding of bluestain-infected wood, but experimental field evidence is lacking. To test the hypothesis that bluestain fungi increase termite presence in infected trees, we inoculated 72 loblolly pine trees in the southeastern USA with one of four bluestain fungi (Ophiostoma minus, O. ips, Leptographium terebrantis, L. procerum), a combination (O. minus + L. terebrantis), or H2O as a control. Over four years, all fungi-inoculated trees formed lesions around injection sites, while control trees formed no lesions except for two contaminated control trees that were excluded from analyses. Bluestain-inoculated trees had increased termite presence in and around fungal lesions, whereas control trees had no termites present. Specifically, termites were present on 35 % of fungi-inoculated trees, presence was consistent over time, and there was no difference among fungal species. This study experimentally demonstrates a link between bluestain fungi and subterranean termites in forests, which could impact tree dynamics post-bluestain infection.